Analysis on leakage factors and their correlation of iodine contrast agent in CT enhanced scanning / 重庆医学

Objective To explore the related factors of contrast agent leakage in CT enhanced scanning and to find out its preventive measures.Methods The clinical data of 46 patients with iodine leakage in the CT enhanced scanning during 2015 were retrospectively analyzed.Results The leakage rate had statistically significant difference between different patient's genders(P＜0.05).The leakage rate was related to the age of the patients(P＜0.01).The leakage rate showed the increasing trend with the increase of injection rate(P＜0.05).The leakage rate was related to the concentration of the contrast agent(P＜0.05).The leakage rate had no increasing trend with the increase of injection dose(P=0.675).The leakage rate was related to the years of injection nurses engaging this working(P＜0.01).Conclusion The leakage rate of female patients was higher than that of male.The older the patients,the greater the contrast agent concentration,the faster the injection rate and the lower the working years of injection nurses,the greater the leakage rate.

Analysis on leakage factors and their correlation of iodine contrast agent in CT enhanced scanning / 重庆医学

Objective To explore the related factors of contrast agent leakage in CT enhanced scanning and to find out its preventive measures.Methods The clinical data of 46 patients with iodine leakage in the CT enhanced scanning during 2015 were retrospectively analyzed.Results The leakage rate had statistically significant difference between different patient's genders(P＜0.05).The leakage rate was related to the age of the patients(P＜0.01).The leakage rate showed the increasing trend with the increase of injection rate(P＜0.05).The leakage rate was related to the concentration of the contrast agent(P＜0.05).The leakage rate had no increasing trend with the increase of injection dose(P=0.675).The leakage rate was related to the years of injection nurses engaging this working(P＜0.01).Conclusion The leakage rate of female patients was higher than that of male.The older the patients,the greater the contrast agent concentration,the faster the injection rate and the lower the working years of injection nurses,the greater the leakage rate.

Image quality evaluation of virtual monoenergetic spectral images obtained in two types of dual energy CT based on noise level / 中华放射学杂志

Objective To investigate the image quality difference of the virtual monochromatic spectral(VMS) images synthesized from fast kilovoltage switching and dual-source dual-energy CT for a given radiation dose. Methods A plurality of disposable syringes containing 15 mg/ml iodine contrast agent and saline were placed on the surface of the male anthropomorphic phantom consisting ofhead neck and torso, GE HD750 gemstone spectral imaging and Siemens Somatom Definition Flash dual energy CT protocols were performed on the phantom for a same dose(volume CT dose index 6.52 mGy), and VMS images (40, 60, 70, 80, 100, 120, 140 keV) were reconstructed and obtained(VMSkV switching and VMSdual-source image), respectively. The objective image noise, iodine signal noise ratio(SNR), iodine contrast noise ratio (CNR) and CT values were measured. The results were analyzed using the paired t test and ANOVA. Results All VMS iodine CT values were gradually decreased with the increasing of keV , and iodine CT values on VMSdual-source images were greater than on VMSkV switching images(P<0.05), VMSkV switching iodine CT values in descending order from the head , chest, abdomen at less than 100 keV,while most VMSdual-source iodine CT values were highest on chest(P<0.05). VMSdual-source and VMSkV switching image noise were highest at 40 keV and successively raised from the head, chest , abdomen. VMSkV switching image noise gradually decreased with the increase of keV in the range of 40 to 70 keV , gradually increased up to the trough after 70 keV from 80 keV gradually decreased, while VMSdual-source image noise was lowest at 70 keV or 80 keV , and then with the keV increased gradually increased. Image noise on VMSkV switching images in the range of 40 to 100 keV were higher than that on VMSdual-source images and lower in the range of 100 to 140 keV at most part(P<0.05). VMSdual-source and VMSkV switching iodine SNR were highest at 40 keV or 60 keV,SNR on VMSdual-source images are greater than on VMSkV switching images except 40 keV images on head and abdomen(P<0.05) . VMSdual-source and VMSkV switching iodine CNR were highest at 60 keV,CNR on VMSdual-source images are greater than on VMSkV switching images except 40 keV images on head 100 keV and 120 keV on abdomen(P<0.05).SNR and CNR decreased from the head, chest, abdomen (P<0.05). Conclusion VMS images synthesized from fast kilovoltage switching and dual-source dual-energy CT have different image quality performance at most keV and body parts, but VMS imaging at approximately 70 keV yielded lower image noise, and at approximately 60 keV yielded highest SNR and CNR.

Evaluation on Ability to Detect the Intracranial Hematoma with Different Density Using C-Arm Cone-beam Computed Tomography Based on Animal Model / 生物医学工程学杂志

This study aims to evaluate the ability of C-arm cone-beam CT to detect intracranial hematomas in canine models. Twenty one healthy canines were divided into seven groups and each group had three animals. Autologous blood and contrast agent (3 mL) were slowly injected into the left/right frontal lobes of each animal. Canines in the first group, the control group, were only injected with autologous blood without contrast agent. Each animal in all the 7 groups was scanned with C-arm cone-beam CT and multislice computed tomography (MSCT) after 5 minutes. The attenuation values and their standard deviations of the hematoma and uniformed brain tissues were measured to calculate the image noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR). A scale with scores 1-3 was used to rate the quality of the reconstructed image of different hematoma as a subjective evaluation, and all the experimental data were processed with statistical treatment. The results revealed that when the density of hematoma was less than 65 HU, hematomata were not very clear on C-arm CT images, and when the density of hematoma was more than 65 HU, hematomata showed clearly on both C-arm CT and MSCT images and the scores of them were close. The coherence between the two physicians was very reliable. The same results were obtained with C-arm cone-beam CT and MSCT grades in measuring SD value, SNR, and CNR. The reasonable choice of density detection range of intracranial hematoma with C-arm cone-beam CT could be effectively applied to monitoring the intracranial hemorrhage during interventional diagnosis and treatment.

Impact of image quality with scan parameters and reconstruction algorithms in head dual-energy computed tomography angiography / 重庆医学

Objective To study the difference of image quality which based on different reconstruction in head dual‐energy computed tomography angiography (DECTA) scanning ,and evaluate the radiation dose which using different tube voltage in DEC‐TA .Methods An anthropomorphic head phantom with simulated arteries was used for DECTA scanning by different scan parame‐ters (tube voltage 80/140 kV and tube voltage 100/140 kV) ,the data was reconstructed with filtered back projection (FBP) and Si‐nogram Affirmed Iterative Reconstruction (SAFIRE) .The CT values with SD were measured and calculate to SNR and CNR ,the dose length product (DLP) was recorded and invert to effective dose .The image quality and radiation dose were evaluated in differ‐ent imaging condition .Results The image noise of SAFIRE reconstruction was lower than FBP reconstruction in same san parame‐ters .The increase of tube current‐time product from 100 mAs to 300 mAs ,it shows the characteristics of linear tendency .When it was on 260 mAs ,the image quality become stable .The difference between the two groups(80/140 kV ,100/140 kV)of SD of CT value by SAFIRE was significant (P0 .05) .The effective doses of group A (80/140 kV) was significantly lower than group B(100/140 kV) .Conclusion Using tube voltage of 80/140 kV combine with SAFIRE algorithm in head DECTA can ensure the image quality ,which can significantly reduce radiation dose .

Patient radiation dose of spine X-ray panoramic imaging: Comparison of two techniques based on Monte Carlo mathematical model / 中华放射医学与防护杂志

Objective To compare patient radiation dose of two techniques of spine X-ray panoramic imaging under the same image quality.Methods An anthropomorphic phantom was used.The reasonable imaging parameters were found for spine panoramic radiography using Sonialvision safire17 Slot scan with HQ mode.And the panoramic films were obtained with different parameters using GE XR650 DR system.The panoramic images were scored by three experienced radiologists.The imaging parameters with the same score in groups were input into PCXMC 2.0 software to get effective dose(E) and organ dose.Results The reasonable imaging parameters of Slot scan were high quality(HQ) mode, SID 150 cm, 100 kVp, and 2 mAs;and the corresponding parameters of XR650 were SID 200 cm, 100 kVp, and 3.2 mAs.The E of the Slot scan with HQ mode, XR650 with manual mode and XR650 with AEC mode was(0.118 7±0.001 4),(0.0847±0.0008), and (0.1580±0.001 5) mSvrespectively, while the E of XR650 with manual mode was lower than the others(F =3 007.293, P ＜0.05).The organ dose using XR650 DR with manual mode were lower than that using Slot scan with HQ mode in all samples except breasts(P ＜0.05);the organ dose using XR650 DR with AEC mode were higher than that using XR650 DR with manual mode and Slot scan with HQ mode for all samples except for thyroid, oesophagus and lungs (P ＜0.05).Conclusions The radiation doses of both spine X-ray panoramic imaging with manual mode are low, and low dose spine X-ray panoramic imaging can be achieved if reasonable parameters are used.

Comparison of pulmonary nodule detection rate and accuracy in low-dose chest CT between iterative reconstruction algorithm and filtered back proj ection algorithm / 吉林大学学报(医学版)

Objective To compare the differences of pulmonary nodule detection rates between iterative reconstruction (sinogram affirmed iterative reconstruction,SAFIRE)algorithm and filtered back projection (FBP) algorithm in chest CT, and to evaluate the detection accuracy.Methods Three groups of tube voltage values of 80,100,and 120 kV were defaulted on the new dual-source CT,with automatic mAs care dose 4D technology, the chest phantom with simulated pulmonary nodules was scanned, then the images were reconstructed with FBP and SAFIRE (grade 1-5 ),respectively. The detection rates of simulated pulmonary nodules in the chest CT images reconstructed of SAFIRE (grade 1-5 )and FBP were compared, and their diameters and CT values were measured.Results With the same tube voltage, no significant difference was found in the detection rate of simulated pulmonary nodules between SAFIRE (grade 1-5 )and FBP (P>0.05 ), the diameter deviation of simulated nodules of SAFIRE (grade 3 )was less than FBP, and the difference in the average CT value of the simulated nodules between SAFIRE (grade 3)and FBP was not statistically significant (P>0.05);the simulated nodule detection rate of 100 kV was equivalent to the detection rate of 120 kV,the simulated nodule (-800 HU and 3 mm )detection rate of 80 kV was less than that of 120 kV;as the tube voltage reduced,or simulated nodule diameter decreased,or the density of simulated nodule reduced,the nodule’s diameter deviation was increased. Conclusion Compared with FBP,the capabilities of SAFIRE in pulmonary nodule detection in different densities and different sizes are same,and SAFIRE algorithm is helpful for accurate displaying of pulmonary nodules,and it can be used for low-dose CT lung cancer screening program.

Analysis of radiation dose to patients during coronary angiography and intracoronary stenting using radial and femoral artery access / 重庆医学

Objective To evaluate the radiation dose to patients using radial and femoral artery access in coronary angiography (CAG) and intracoronary stenting (IS) ,provide basis for clinical intervention path .Methods The data of 190 samples (43 by femo-ral and 147 by radial) underwent CAG and 54 samples (17 by femoral and 37 by radial) underwent CAG+IS were analyzed retro-spectively .All samples were divided into two groups (radial group and femoral group) by different approach ,and radiation dose in different approach were analyzed .Results There was no significant difference of Dose Area Product (DAP) and Cumulative Dose (CD) using femoral and radial access in CAG (P>0 .05) .Separating two samples which CD were much higher than others ,the mean DAP was 23 .93 Gy · cm2 and the mean CD was 358 .85 mGy using radial vs .27 .06 Gy · cm2 and 369 .57 mGy using femoral , not distinctive either(P=0 .734 ,P=0 .834) .In CAG+IS ,the mean DAP was 82 .64 Gy · cm2 using radial and it was 78 .11 Gy · cm2 using femoral ,and the mean CD was 1 286 .41 mGy using radial and it was 1 267 .76 mGy using femoral .There were no signifi-cant difference in both DAP and CD (P=0 .705 ,P= 0 .919) .Conclusion The radiation dose of DAP and CD were not different when using radial access and using femoral access in CAG and CAG +IS .

Application of Monte Carlo software in estimating patients' radiation dose during CCTA and confirmation by anthropomorphic phantom study / 中华放射医学与防护杂志

Objective To evaluate the accuracy and efficiency of the Monte Carlo software in measuring the radiation dose to the patients who received the CCTA (Coronary Computed Tomography Angiography) examination.Methods A anthropomorphic chest phantom underwent CCTA using three scan parameters (tube voltage 80 kV,100 kV and 120 kV).Computer Software ImpactDose 2.0 was used to compute the chest organ dose on the basis of the three groups tube voltage CT scan characteristic,and the stimulation results of ImpactDose 2.0 software was verified by use of anthropomorphic phantom thermoluminescence dosimeter experiment method.Results For all the measured organs except for lung,the absorbed organ dose and effective dose of three groups of tube voltages of CCTA measured by the InpactDose 2.0 was lower than those as measured by anthropomorphic phantom study.The relative error of both methods was within ± 50％.Conclusions Monte Carlo software can be used to estimate the levels of radiation dose during CCTA examination with a tolerable error within the acceptable range.

Correlation of acquisition time of C-arm cone-beam CT with image quality and radiation doseduring cerebral angiography using an anthropomorphic head phantom / 中华放射学杂志

Objective To investigate the influence of acquisition time of C-arm cone-beam CT on image quality and radiation dose of cerebral angiography.Methods C-arm cone-beam CT of cerebral angiography was performed on the male anthropomorphic head phantom,with DynaCT imaging mode and the acquisition time of 5 s,8 s and 20 s were used.Scanning was performed with each acquisition time for three times,and VR,MIP and MPR images were reconstructed.The attenuation values and their standard deviations of intracranial segment of the internal carotid artery (ICA),middle cerebral artery(MCA),anterior cerebral artery(ACA) and uniformed brain tissues were measured to calculate the image noise,signal to noise ratio (SNR) and contrast to noise ratio (CNR).We used the image noise,SNR and CNR as the objective standard to evaluate the image quality,and One-way ANOVA analysis of variance was used to assess the difference among them.A scale with scores 1 to 5 was used to rate the quality of the reconstructed image of ICA,MCA,ACA as a subjective evaluation,the difference among the evaluation scores were analyzed using Kruskal-wallis.We recorded the dose area product (DAP) of each acquisition time and the effective dose(ED) was calculated to assess the radiation dose,the difference among them were analyzed using One-way ANOVA analysis of variance.Results In C-arm cone beam CT 20 s imaging,the SNR of intracranial segment of the ICA,M CA,ACA were 22.29± 1.41,29.36 ±0.11 and 23.13 ±2.10 respectively,in 5 s imaging13.83 ±0.61,14.65 ±0.16 and 12.79±0.19 respectively,in 8 s imaging 14.92±0.96,18.97 ± 1.24 and 16.65 ±0.46 respectively,all the results showed a significant difference (F valued 58.19,327.29,52.74 respectively,all P valued＜0.01),the CNR of 20 s imaging were higher than that of 5 s and 8 s imaging,the Noise of ICA,MCA,ACA and the uniformed brain tissues of 20 s imaging were lower than that of 5 s and 8 s imaging,all the results showed significant difference (all P valued＜0.01).The subjective evaluation scores of VR imaging of 5 s,8 s and 20 s were 3.61 ±0.49,4.06±0.53,4.72±0.45 respectively,the scores of MIP imaging were 3.42±0.50,3.83±0.65 and 4.50±0.51 respectively,the scores of MPR imaging were 2.83±0.45,3.14±0.35 and 3.67±0.49 respectively,all the results showed significant difference (x2 valued 51.29,42.25 and 43.56 respectively,all P valued ＜0.01).The DAP values in C-arm cone beam CT 5 s,8 s and 20 s imaging were (9.11 ±0.18),(13.81±0.75)and(58.62±0.62)Gy· cm2,ED values were (0.91 ±0.02),(1.38±0.75)and(5.84± 0.11) mSv,all the results showed significant difference (F valued 3 720.30 and 3 654.85 respectively,all P valued＜0.01).Conclusion The image quality and radiation dose of C-arm cone-beam computed tomography are closely correlated with acquisition time.

Design and application of the telemedicine system / 重庆医学

Objective In response to the requirements of the new nation health care reform for the first diagnosis sinking .To in‐vestigate hospital as the center ,radiation surrounding ,we build the telemedicine system .Methods We analyzed the requirement ,de‐sign the architecture of the system through the way of TOGAF .Results The telemedicine system including telemedicine ,remote diagnosis and distance education was built .Conclusion The design ,establishment and application of the telemedicine system has an important influence and meaning .

Surgical treatment and early postoperative enteral nutrition of acute obstruction caused by colorectal cancer / 中国综合临床

Objective To investigate the method of surgical treatment of acute intestinal obstruction caused by colorectal cancer,and affirm the feasibility and validity of the new way ofearly precolonic postoperative enteral nutritionafter operation of acute intestinal obstruction caused by colorectal cancer.Methods Retrospective analized the clinical data of 78 cases of acute intestinal obstruction caused by colorectal caner from September 2007 to September 2012 and the incidence of complications (incision infection,intra-abdominal abscess,anastomotic leakage,and pneumonia) was observed.Results Sixty-two patients received radical resection and primary anastomosis.All of them were cured and no death occurred.Two patients had complication of postoperative infection and none suffered from anastomotic or drainage leakage.Conclusion Radical resection and primary anastomosis using Intra-operative colonic lavage are safe and effective methods for patients with colorectal cancer associated with acute intestinal obstruction,and early precolonic postoperative enteral nutritioncould better eliminate perioperative malnourished patients more,reduce operation complication,prevent anastomotic leakage,and increase the success rate of the operation.

Clinical application of low-dose chest CT on diagnostic imaging for AIDS patients with normal PCP weight / 重庆医学

Objective To evaluate the feasibility and establish the corresponding scanning plan through the clinical application of low-dose CT on diagnostic imaging for 111 AIDS patients with pnenmocystsis carinii pneumonia (PCP)and normal weight .Methods The thesis applied American GE(General Electric Company )FII double-row spiral CT scanner and the kV value is fixed to be 120 kV with the conventional dose (automatic mAs) and low-dose scanning applied respectively during the diagnosis .Meanwhile ,the low-dose scanning was carried out randomly in 50 mAs(50 mAs group) ,40 mAs(40 mAs group) and 30 mAs(30 mAs group) ,and then ,the iconographical imaging quality and radiation dose were analyzed ,the respective low-dose scanning plans was formulated at last .Results The high-quality film ratios for conventional close and 50 mAs group were 70 .3% and 62 .2% respectively ,and the good film ratios were 29 .7% and 37 .8% ,while no poor films occurred in both groups .The high-quality film ratios for conventional close and 40 mAs were 67 .6% and 56 .8% ,the the good film ratios were 32 .4% and 43 .2% and no poor films ,either .The high-quality film ratios for conventional close and 30 mAs were 70 .3% and 56 .8% ,the good were 29 .7% ,43 .2% and no poor films showed between both groups .From the results ,the consequential imaging films mainly show high and good quality ,all films meet the imaging diagnosis requirements and the difference are not statistically significant (P> 0 .05) .The radiation doses of conventional dose and low dose scanning (50 mAs ,40 mAs and 30 mAs groups) were 7 .6 mGy ,2 .6 mGy ,2 .1 mGy and 1 .5 mGy respectively , while the least radiation doses was for 30 mAs group and the corresponding dose is only 19 .8% of the original .The results from 111 patients applied conventional dose (automatic mAs) and low dose scanning all meet the imaging diagnosis requirements without any missed or erroneous diagnosis .Conclusion The chest low-dose CT scanning for AIDS patients with PCP and normal weight can fully meet the clinical diagnosis and treatment ,so it is practical and feasible .Meanwhile ,the conventional-dose scanning can be ap-plied at first and low-dose CT scanning later for reexamination to ensure the stability of image quality .For low-dose chest CT scan-ning ,the voltage fixed is 120 kV and the current 30 mAs .

Correlation between the tube current and image noise in low-dose chest CT scean / 中华放射医学与防护杂志

Objective To analyze the distribution of image noise in low-dose chest CT scan and optimize the relative scanning parameters.Methods The CT images of the Chinese anthropomorphic chest phantom( CDP-1 C) were simulated into six groups of low-dose images with different noise indexs by using an image noise addition tool.The difference between the preset noise index and analog noise value was compared.The CT images of 20 volunteers were also simulated into nine groups of low dose scans with the tube currents of 10,30,50,80,100,120,150,180 and 240 mA.The noise values of images were recorded and analyzed.Results There was no statistical difference between the analog noise value and the noise index.The image noise of low-dose chest scan was increased with the decrease of tube current.The noise was increased quickly when the current was decreased from 50 to 30 mA ( F =24.09 - 40.79,P ＜ 0.05),but the noise increased slowly when the current decreased from 240 to 80 mA.There was no statistical difference between the noise of 80 mA group and that of 120 mA(P ＞ 0.05).Conclusions The noise addition tool can be used to evaluate the image noise of low-dose chest CT scan.Adoption of 80 mA in chest CT scan would result in low radiation dose without adding image noise.

An experimental study of comparing digital tomosynthesis and multi-slice CT scanning for the detection of pulmonary nodules using the anthropomorphic chest phantom / 中华放射学杂志

ObjectiveTo compare detection rate of pulmonary nodules and the radiation doses of digital tomosynthesis (DTS) and MSCT chest scanning by using the anthropomorphic chest phantom which containsthermoluminescent dosimeters( TLD ) and simulated pulmonary nodules.Methods The radiation doses of DTS and MSCT scanning were measured by using the anthropomorphic chest phantom which contains 45 TLD and simulated pulmonary nodules.The radiation doses of najor organs were converted into effective dose ( ED ). Three radiologists of different clinical experiences independently reviewed and recorded the density,diameter and position of pulmonary nodules.The sensitivity of nodule detection by DTS and MSCT were compared by Fisher exact test and Chi-square test. The paired t test was conducted to analyze the dose levels of DTS and MSCT.ResultsThe sensitivity of detection nodule by DTS and MSCT were 66.7％ (30/45) and 91.1％ (41/45) respectively.Statistically significant difference between the two examinations existed ( x2 =8.073,P ＜ 0.05).The sensitivity of detection - 650 HU ground glass opacity pulmonary nodule by MSCT and DTS were 93.3％ (14/15) and 73.3％ (11/15) respectively.There was no significant difference between DTS and MSCT ( P ＞ 0.05 ).The sensitivity of detection - 800 HU ground glass opacity nodule and ground glass opacity nodule (d ＜ 8 mm) by DTS were 33.3％ (5/15) and 16.7％ (2/12) respectively,which were lower than those by CT[80.0％ (12/15) and 66.7％ (8/12)].The radiation doses of DTS for various organs in the chest were lower than those of CT. Statistical significant difference between DTS and MSCT existed ( lung t =19.69,thoracic vertebral t =30.01,heart t =16.33,liver t =5.06,breast t =9.43,thyroid gland t =8.05 ;P ＜ 0.05).The effective doses of the DTS and MSCT were 0.65 and 7.71 mSv respectively.ConclusionsThere is no difference between the DTS and MSCT in the detection rate of -650 HU ground glass opacity nodule.For detecting the ground glass opacity nodule ( - 800 HU) and ground glass opacity nodule (d ＜ 8 mm),MSCT is superior to DTS. However,the radiation dosage of DTS is 8.41％ of the MSCT scanning.

The clinical application of hydrogen magnetic resonance spectroscopy combining with diffusion weight imaging in brain gliomas grading / 生物医学工程学杂志

The present study was aimed to investigate the function of diffusion weight imaging (DWI) combining with magnetic resonance spectroscopy (MRS) in the grading of brain gliomas. 12 cases low grade and 17 cases high grade of brain gliomas patients were examined with DWI and MRS, with all tumors confirmed by pathology in advance. The apparent diffusion coefficient (ADC) values, their corresponding metabolite ratios of Cho/Cr, Cho/NAA and tumor cellularities of tumor solid enhanced parts were measured. The ratios of Cho/Cr and Cho/NAA and their corresponding ADC values had significant differences between their high and low grade gliomas values, respectively. The ADC values demonstrated a negative correlation with Cho/Cr, Cho/NAA, and a significant negative correlated with Cho/Cr. And the ADC values demonstrated strong negative correlations with tumor cellularities. DWI combining with MRS could provide more valuable information in evaluating gliomas grading.

The measurement of organic radiation dose of multi-slice CT scanning by using the Chinese anthropomorphic chest phantom / 中华放射学杂志

Objective Using the Chinese anthropomorphic chest phantom to measure the absorbed dose of various tissues and organs under different noise index, and to assess the radiation dose of MSCT chest scanning with the effective dose(ED). Methods The equivalence of the Chinese anthropomorphic chest phantom(CDP-1C) and the adult chest on CT sectional anatomy and X-ray attenuation was demonstrated. The absorbed doses of various tissues and organs under different noise index were measured by laying thermoluminescent dosimeters(TLD) inside the phantom, and the corresponding dose-length products(DLP) were recorded. Both of them were later converted into ED and comparison was conducted to analyze the dose levels of chest CT scanning with automatic tube current modulation (ATCM) under different noise index. Student t-test was applied using SPSS 12.0 statistical software. Results The Phantom was similar to the human body on CT sectional anatomy. The average CT value of phantom are -788.04 HU in lung,45.64 HU in heart,65.84 HU in liver,254.32 HU in spine and the deviations are 0.10%,3.04%, 4.49% and 4.36% respectively compared to humans. The difference of average CT value of liver was statistically significant(t=-8.705,P＜0.05),while the differences of average CT values of lung, heart and spine were not significant(t value were -0.752,-1.219,-1.138,respectively and P＞0.05).As the noise index increased from 8.5 to 22.5, the DLP decreased from 393.57 mGy·cm to 78.75 mGy·cm and the organs dose declined. For example, the average absorbed dose decreased from 22.38 mGy to 3.66 mGy in lung. Compared to ED calculating by absorbed dose, the ED calculating by DLP was lower. The ED values of the two methods were 6.69 mSv and 8.77 mSv when the noise index was set at 8.5. Conclusions Application of the Chinese anthropomorphic chest phantom to carry out CT dose assessment is more accurate. The noise index should be set more than 8.5 during the chest CT scanning based on ATCM technique.

Experimental study of rotational DSA on image deformation and measurement error / 中国医学影像技术

Objective To evaluate the image deformation and measurement error of rotational DSA by model experiment. Methods Five steel balls (diameter: 20 mm) were placed in a horizontal space of 30 mm, the middle of which was as the isocenter for rotational DSA acquisition. Another 5 steel balls (diameter: 10 mm) were placed in a vertical space of 30 mm with the same alignment for rotational DSA acquisition. The screen was divided into five regions and the morphological changes of the ball image were observed at each rotation angle. The experimental images of the left anterior oblique ball images at 20°, 40°and 60° among each two groups were selected and measured by automatic isocenter calibration and sphere calibration respectively, and compared with the actual diameters of balls to calculate the image magnification. Results Except the center one, other balls were of deformation at different rotation angles due to the distance to the detector leading to enlargement and reduction. With automatic isocenter calibration, only the diameter of the center ball corresponded with the actual one, the distance away from the center or the rotation angle was inversely proportional to measurement error (maximum magnification 12.42%).With sphere calibration, the measurement results in various regions at different rotation angle were basically the same, with smaller measurement error (maximum magnification 3.41%). Conclusion Placing the organ of interest in the center area can reduce image distortion in rotational DSA imaging. Selecting reasonable measuring technology according to the lesion location is helpful to control measurement errors.

Clinical effect of three different pancreaticojejunostomy in Whipple / 中国基层医药

Objective To investigate the clinical results of end-to-end invagination pancreaticojejunostomy.end-to-end invagination pancreaticojejunostomy and duct-to-mucosa pancreaticojejunostomy of pancreaticoduodencetomy of patients with pancreatic and periampullary carcinoma. Methods Fifty-two patients underwent different pancreaticoduodenectomy in our hospital from August 1995 to July 2006 were collected and analyzed retrospectively.The incidence of pancreatic leakage,operation time,the blood loss and the postoperative complications were analyzed. Results Twenty-five patients received end-to-end invagination pancreaticojejunostomy.Sixteen patients received end-toside invagination pancreaticojejunostomy.Eleven patients received end-to-side pancreaticojejunal mucosa-mucosa anastomosis.The operation time of the duct-to-mucosa pancreaticojejunostomy was shorter than the two of the others(4 ～7.15 h).The perioperative comphcations occurred in 18 cases and the long-term postoperative complications occurred in 10 cases.The average length of stay in hospital was(19.32 ±5.45)days.Two cases died during perioperative period. Conclusion End-to-eed invagination pancreaticojejunostomy,end-to-side invagination pancreaticojejunostomy and end-to-side pancreaticojejunal mucosa-mucosa anastomosis are all common anastomosis methods.Pancreatic leakage is a serious postoperative complication.The selection of anastomosis method is based on the condition during operation.

The clinical analysis of the palliative drainage to pancreatic and periampullary carcinoma / 中国基层医药

Objective To compare the clinical effects of palliative drainage to pancreatic and periampullary carcinoma which could not be excised with the operation.Methotis A retrospective study was accomplished on the palliative drainage treatment of 68 patients with pancreatic and petiampullary carcinoma hospitalized from 1996 to 2003.Results The disease course was two days to eight months.A definite preoperative diagnosis was made for 64 cases.Among them.single test diagnosed 24 cases and multiple tests diagnosed 40 cases.56 patients suffered from jaundice before operation.34 patients were treated by Roux-Y choledochojejunostomy.Choledochoduodenostomy was performed in 16 patients,cholecystduodenostomy for biliary by pass Was performed in 8 patients and stented internal drainage of the biliary duct in the liver and duodenostomy was performed in 10 patients.After reducing jaundice,12 patients was performed surgical resection.The second operation was performed in 4 patients because of postoperative jaundice and in 3 patients because of pylofic obstruction.The pefioperative compllcations include 4 cases of jaundice pyloric,3 cases of obstruction,2 cases of postoperative bleeding and 5 cases of infection of incisional wound.The aver-age stay in hospital waa 13.3 days(8～22 days).Conclusion Multiple tests were helpful to make a definite preoper-ative diagnosis.The selection of palliative drainage method based on the condition of patients had good curative effect in clinic.Surgocal exploration and reducing jaundice could set win conditions for second operation.